Conveying apparatus having vacuum type holding means

ABSTRACT

A lifting apparatus including a cylinder having at its lower end a flexible holding pad adapted to be placed on the surface of a body to be conveyed, a piston air-tightly received in the cylinder, and a piston rod secured to the piston and extending through the upper end of the cylinder, the projecting end portion of the piston rod being adapted to be used for the purpose of hanging the apparatus, characterized by a bottom plate arranged at a position displaced inwardly toward the cylinder from a plane including the peripheral edge of the holding pad, a valve provided in the piston for controlling the communication between said cylinder and the holding pad, and depressing means confronting to said bottom plate and adapted to control said valve, whereby said valve is automatically controlled each time when the apparatus is placed on the body to be conveyed so that the vacuum is alternately established in and released from the cylinder.

United StatesPatlit 4 H 1 I Yoda-ct al.

[4 1 Sept. rams CONVEYING APPARATUS HAVING VACUUM TYPE HOLDING MEANS[75] Inventors: ,Mikio Yoda; Shinnosuke Ishida;

Haluo Ashizawa, all of Hitachi-shi, Japan 7 [73] Assignee: Hitachi,Ltd., Tokyo, Japan [22] Filed: Aug. 10, 1971 [21] Appl. No.: 170,593

[30] Foreign Application Priority Data Aug. 12, 1970 Japan 45/7007] [52]U.S. Cl 294/64 R [51] Int. Cl. B66c 1/02 [58] Field of Search 294/64 R,65

[56] References Cited- UNITED STATES PATENTS 3,431,0l0 3/1969 Glanemann294/64 R Primary Examiner-Even C. Blunk 7 Assistant Examiner-Johnny D.Cherry Attorney-Craig, Antonelli and Hill 8 n my l2 [57] ABSTRACT Alifting apparatus including a cylinder having at its lower end aflexible holding pad adapted to be placed on the surface of a body to beconveyed, a piston airtightly received in the cylinder, and a piston rodsecured to the piston and extending through the upper end of thecylinder, the projecting end portion of the piston rod being adapted tobe used for the purpose of hanging the apparatus, characterized by abottom plate arranged at a position displaced inwardly toward thecylinder from a plane including the peripheral edge of the holding pad,avalve provided in the piston for controlling the communication betweensaid cylinder and the holding pad, and depressing means confronting tosaid bottom plate and adapted to control said valve, whereby said valveis automatically controlled each time-when the apparatus is placed onthe body to be conveyedso that the vacuum is alternately established inand released from the cylinder.

4 Claims, 12 Drawing Figures llll PATENIED SEPI 8l973 SHLU 3 0F 4 FIG. 4

FIG. 5

INVENTORS NWO YODA .SHINNOSUKE I HwA HALUO ASHIZAWA BY GMtuhdQ; '6 H492ATTORNEY S a body to be conveyed irrespective as to whether the body ismagnetic or non-magnetic in nature.-

Such a known vacuum holder type lifting apparatus includes such a typein which a vacuum pump is provided for evacuating a holding pad which isplaced against a body to be conveyed, as well as a pumpless type inwhich the weight of a body to be conveyed is utilized for producing arelative movement between a cylinder and a piston air-tightly engaged inthe cylinder so as to produce a vacuum therein which vacuum is utilizedto evacuate the holding pad.

Recently, the pumpless type which does not require any power source fordriving the vacuum has widely been used as a portable type due to itsconvenience in use.

The former type in which a vacuum pump is used has an advantage in thatthe vacuum in the holding pad can readily be established or releasedthrough the use of a solenoid valve for gripping a body to be conveyed,carrying it to a desired position and releasing it. In contrast to this,in the latter type, that is, the pumpless type which does not requireany power source, it is not recommendable to use a solenoid valve whichrequires a power source, because the use of a solenoid will reduce theadvantages of this type as a portable lifting apparatus and also makesit impossible to use the apparatus at a site where the power is notavailable.

Therefore, it has been proposed to provide in the pumpless type liftingapparatus a manually operated valve which is adapted to be manuallyclosed after the holding pad is placed on the surface of a body to beconveyed, so that the apparatus becomes ready for lifting the body.

Then the body is conveyed to a desired position, the apparatus islowered until the body sits on the floor. Thereafter, the valve ismanually opened and the apparatus is lifted. Since the vacuum in theholding pad is released in this position, the body can be released fromthe pad.

In this type of lifting apparatus which has a manually operated valve,an operator must always actuate the valve for holding and releasing abody to be conveyed, so that the apparatus cannot be used for handling abody placed on an elevated position.

An object of the present invention is to provide a vacuum holder typelifting apparatus which can hold and release a body to be conveyedirrespective of the elevation of the body without requiring any manualoperation.

Another object of the present invention is to provide a vacuum holdertype lifting apparatus which can be positively and automaticallyoperated irrespective of the surface condition of a body to be conveyed.

In order to achieve these objects, the present invention provides avacuum holder type lifting apparatus comprising a cylinder having at itslower end a flexible holding pad adapted to be placed against thesurface of a body to be conveyed, a piston air-tightly received in thecylinder, a piston rod secured to the piston and extending through theupper portion of said cylinder, and an eye portion provided at theprojecting end of the piston rod to be engaged by a crane and the liketo lift the apparatus, characterized by a bottom plate having a venthole and disposed at a position displaced inwardly toward the cylinderfrom a plane including the peripheral edge of said holding pad, a valveprovided in said piston for controlling the communication between thecylinder and the holding pad, and a depressing portion confronting tosaid bottom plate for controlling said valve.

Further, said valve is opened or closed when the depressing portion isdisplaced through the engagement with the bottom plate and thereafterreturned to its original position by being released from the bottomplate, and closed or opened when the depressing portion is subsequentlydisplaced through the engagement with the bottom plate and thereafterreturned to its original position by being released from the bottomplate.

The detail of the arrangement will become apparent from the descriptionsof preferred embodiments of the present invention.

With the arrangement of the present invention in which the depressingportion for controlling the valve is placed in a confronting relationwith respect to the bottom plate, the valve can be positively controlledirrespective of the surface condition of a body to be conveyed.

FIG. 1 is a longitudinal sectional view showing one embodiment of thevacuum holder type lifting apparatus in accordance with the presentinvention;

FIG. 2 is a perspective view showing an example of the valve used in theapparatus embodying the present invention;

FIG. 3 is a longitudinal sectional view taken along the line III III inFIG. 2;

FIG. 4 is an exploded perspective view of the valve;

FIG. 5 is an enlarged perspective view showing a first and a second sawtooth control elements;

FIG. 6 is an expanded view of a cam in the saw tooth control element;and

FIGS. 7a-7 f are diagrammatic views showing the sequence of the controlof the valve.

FIG. 1 shows a typical example of a pumpless vacuum holder type liftingapparatus embodying the present invention and comprising a cylinder 1, apiston 2 received in the cylinder 1, a piston rod 3, a hoist fitting 4secured to the upper end of the piston rod 3, and a holding pad 5secured to the lower end of the cylinder 1.

The cylinder 1 includes an upper cylinder unit 1a and a lower cylinderunit 1b which are secured together at their opposed flanges 6 and 7 bymeans of bolts 8 and nuts 9.

The upper cylinder unit la includes an upper wall 10 having at itscenter a bearing part 11 for passing said piston rod 3 therethrough. Abearing 12 is secured to the bearing part 11 and guides the piston rod 3for vertical movement. The bearing 12 is held in position by means of aholding plate 14 secured to the upper wall 10 by means of bolts 13.

The lower cylinder unit lb receives said piston '2 which is secured tothe piston rod 3. In order to separate the cylinder 1 air-tightly intotwo units, a diaphragm 15 is secured at its one edge to the uppersurface of the piston 2 by means of a plate 16 and clamping bolts 17 andat the other end between the flanges 6 and 7 of the upper and lowercylinder units la and 1b, respectively. The diaphragm 15 may be acylindrical one comprising a Tetron clothing coated by rubber material.Said other end of the diaphragm 15 is provided with a bead 18 so thatthe diaphragm 15 is securely held in the bead 18 for the purpose ofair-tightly separating the cylinder units la and lb.

The holding pad is secured to the lower part of the cylinder 1. The pad5 is made of a flexible but strong material such as natural or syntheticrubber and so formed that it can engage with the lower peripheral edgeof the cylinder 1. A bottom plate 19 is provided for securing theholding pad 5 to the cylinder 1.

The bottom plate 19 has an air port 20 formed at an appropriate portionand is adapted to engage with the lower surface of the piston 2 so as tolimit the lower stroke end thereof. The holding pad 5 is secured betweenthe bottom plate 19 and the lower edge of the cylinder 1 by means ofscrews 21.

It should of course be noted that the holding pad 5 can be secured tothe cylinder 1 by any known means other than the bottom plate 19. Forexample, the holding pad 5 may be fitted to the inner or outer peripheryof the lower part of the cylinder 1 and secured thereto by means of aband or a ring tightened by screws.

The air port 20 formed in the bottom plate 19 serves to pass the airtaken into the cylinder when the piston 2 is moved upwardly in thecylinder under a no load condition. In order to prevent dust or foreignmaterial taken into the cylinder 1, a filter 22 is secured to the bottomplate 19 by screws 23. A dial gauge type vacuum indicator 24 is securedto the side wall of the lower cylinder unit 1b for monitoring thepressure in the lower cylinder unit 1b. The piston 2 is provided with anopening 25 for making communication between the upper and lower cylinderunits 1a and 1b. In the opening 25, a valve 26 is air-tightly mountedfor the purpose which will be described later in detail.

The valve 26 is provided with a depressing portion 27 which is adaptedto be placed against the bottom plate and senses a fact that the piston2 abuts the bottom plate 19.

In the aforementioned description, the upper and lower cylinder units laand lb of the cylinder have been separately prepared and connectedtogether, however, they may be formed integrally. In the latterarrangement, the upper wall of the cylinder 1 may be in the form of alid and the diaphragm may be held between the upper wall 10 and thecylinder 1.

The aforementioned valve 26 is shown by an elevational view in FIG. 2.The detail of the valve 26 will now be described taking reference toFIGS. 2 through 4.

The reference numeral 28 shows a cylindrical casing of the valve 26which has on its inner surface spiral grooves 29 and 30 and at itscentral portion an inwardly projecting annular wall 32 which provides avalve seat 31.

The projecting wall 32 is provided at its central portion with anopening 33 for providing an air passage. A first cylindrical body 35having a valve closing compression spring 34 is mounted on the upperpart of the cylindrical casing 28 by a spiral groove 36 formed on theouter surface of the body 35 and the co-operating spiral groove 29formed on the casing 28. The cylindrical body 35 is provided with aplurality of air ports 37 for communicating the exterior and theinterior of the cylindrical casing 28 together.

The reference numeral 38 shows a valve body which comprises a plate 40secured to the upper end of a valve rod 39 and a valve member 43 made ofa flexible material secured to the plate 40 by a holding plate 41 and anut 42. The valve rod 39 has a semi-spherical end 44 projecting from thenut 42 and the projecting end 44 is so arranged as to co-operate with arecess 46 formed on the lower surface of a spring seat 45 supporting thevalve spring 34. The valve rod 39 is provided at its lower end with afirst saw teeth element 47 for controlling the valve body 38. Thecylindrical casing 28 receives at its lower part a second cylindricalbody 49 having a plurality of air ports 48 and secured to thecylindrical casing 28 by a spiral groove 50 en gaging with the spiralgroove 30 in the casing. The second cylindrical body 49 is provided atits center portion with an axial hole 52 having ribs 52a and adapted toguide the second saw teeth element 51 co-operating with the first sawteeth element 47. Further, the second cylindrical body 49 is provided atits lower outer periphery with a flange 53 extending radially outwardlyfrom the cylindrical casing 28. The flange 53 has a plu rality of holes54 for inserting screws to mount the valve 26 at the opening 25 of thepiston 2 as shown in FIG. 1. A packing 55 is disposed between the loweredge of the cylindrical casing 28 and the body 49 so as to ensure anair-tight seal therebetween. The valve rod 56 having the second sawteeth control element 51 is further provided at its lower end with aspring seat 58 secured by means of a screw 59 for supporting compressionsprings 57 constantly biasing the valve rod 56 downwardly. The head ofthe screw 59 serves as the aforementioned depressing portion 27 of thevalve 26. The upper end of each compression spring 57 seats on one ofshoulder portions 60 formed in the air passages 48, and the lower endthereof engages with a recess 61 formed on the upper surface of thevalve seat 58.

The details of the first and second saw teeth control elements 47 and 51will now be described taking reference to FIGS. 5 and 6. The firstcontrol element 47 has a pair of cams 66a and 66b each comprising afirst tooth 63 having a surface 62 of predetermined inclination angleand a second tooth 65 having a surface 64 of an inclination anglesubstantially the same as the angle of the surface 62. Slits 67a and 67bare formed between the cams 66a and 66b for co-operating with the ribs52a on the hole 52 of the second cylindrical body 49.

The second control element 51 comprises a pair of cams a and 70b eachhaving a tooth (69) having a surface 68 of an inclination anglecorresponding to the angle of the surface 62 or 64. Slits 71a and 71bare formed between the cams 70a and 70b for co-operating with the ribs520.

In the embodiment illustrated in FIG. 6, the angular width 0 of thetooth 63 in the cam 66a or 66b may be for example the angular width 6 ofthe second tooth 65 may be for example 45 and the angular width 0 of theslit 67 may be 45. With respect to the cam 70a or 70b, the angular width0 of the tooth 69 may be for example 50 and the width of the slit 71 maybe the same as the width 6 The angular width 0,, shows a flat areabetween the tooth 69 and the slit 71.

The operation of the valve 26 will now be described in connection withthe operation of the lifting apparatus shown in FIG. 1. When the liftingapparatus is placed on a body 100 to be conveyed, the piston 2 islowered due to its own weight as shown in the drawing. In this position,the depressing portion 27 of the valve 26 engages with the bottom plate19. Since the portion 27 is depressed upwardly, the valve rod 56 ismoved in the opening 52 of the second cylindrical body 49 up wardlyagainst the action of the compression spring 57. Thus, the tooth 69 ofthe second saw tooth control element 51 engages with the tooth 65 of thefirst saw teeth control element 47 as shown in FIG. 7b so as to push thelatter upwardly as shown in FIG. 7c.

As the first saw teeth control element 47 is thus moved upwardly, thevalve body 38 is also slightly moved upwardly through the valve rod 39.With this upward movement, the first saw teeth control element 47 movesslightly apart from the tooth 69, and the tooth 65 on the element 47engages with the slanted surface 52b of the rib 52a.

Thereafter, the hoist fitting 4 on the piston rod 3 is lifted forexample by a crane, the piston 2 is moved upwardly in the cylinder 1. Asthe piston 2 moves upwardly, the depressing portion 27 is released fromthe bottom plate 19 and caused to move downwardly by the compressionspring 57. Thus, the second saw teeth control element 51 is also moveddownwardly when the depressing portion 27 is lowered. At this instance,the tooth 65 of the first saw teeth control element 47 slides along thesurface 52b of the rib 52a as shown in FIG. 7d and thereafter downwardlyalong the ribs 52a at its slits 67a into the opening 52. The positionthus obtained is shown in FIG. 7f. Thus, the valve member 43 on thevalve body 38 is placed in sealing contact with the valve seat 31 so asto close the opening 33.

The compression spring 34 serves at this moment to lower the first sawteeth control element 47. As the piston 2 moves further upwardly in thecylinder 1 after the valve is closed, the inside of the cylinder unit lbis evacuated. Thus, the space between the holding pad 5 and the body 100is also evacuated so that the body 100 is securely held by the holdingpad 5.

When the piston 2 is sufficiently moved upwardly, the weight of the body100 is balanced with the holding vacuum force in the pad 5 and therelative movement between the cylinder 1 and the piston 2 is terminated.Therefore, a further lifting of the apparatus effectively lifts the body100 held thereby. The vacuum pressure in the lower cylinder unit 1b isindicated by the vacuum indicator 24.

The operation of the apparatus will further be described with respect tolowering of the body 100.

When the lifted body 100 is placed on a floor, the piston 2' again abutsthe bottom plate 19 so that the per tion 27 is again moved upwardly.Then, the tooth 69 of the second saw teeth control element 51 serves topush the tooth 63 of the first saw teeth control element 47 upwardly sothat the tooth 63 is placed at the level of the surface 52b. Thus, whenthe piston 2 is again lifted, the surface 62 of the tooth 63 engageswith the surface 52b of the rib 52a as shown in FIG. 7a.

Therefore, in this position, the valve 26 is opened as shown in FIG. 3.Therefore, when the apparatus is lifted, the air in the upper cylinderunit 1a is allowed to flow through the valve 26 into the lower cylinderunit lb as shown by the arrow in the drawing. Thus, the inside of theholding pad 5 is not evacuated and the apparatus releases the body 100.

In the above embodiment, the first saw teeth control element 47 isintegrally formed with the valve rod 39 and the valve body 33 ispivotally mounted so that it can pivot with respect to the spring seat43, however, it should of course be noted that the first saw teethcontrol element 47 may be so mounted that it can pivot with respect tothe valve rod 39.

We claim:

ll. A vacuum holder type lifting apparatus comprising a substantiallylongitudinally disposed cylinder provided at the lower end thereof witha flexible holding pad co-operating with the plane of a body to beconveyed, a piston air-tightly received in the cylinder and operated tomove up-and-down, and a piston rod connected at the lower end thereofwith said piston and provided at the upper end thereof with a hoistfitting, said upper end of said piston rod projecting from the upperportion of said cylinder so as to be guided, characterized in that thevacuum holder type lifting apparatus includes a bottom plate disposedslightly inwardly of the cylinder from a plane defined by the peripheraledge of the holding pad, said bottom plate being provided with a venthole, and a change-over valve provided in the piston for selectivelyconnecting upper and lower spaces formed in said cylinder andpartitioned by said piston with each other, and that the change-overvalve includes a valve seat, a valve body opposed to said valve seat andsupported rotatably, means for biasing said valve body toward a valveclosing direction, a first saw tooth control element secured to thelower end of said valve body and provided at the lower portion of saidfirst element with at least a pair of circumferentially disposed teethdifferent in height from each other, and a second saw tooth controlelement provided at the upper portion thereof with teeth opposed to saidfirst saw tooth control element and provided at the lower portionthereof with a depressing portion opposed to the bottom plate.

2. A vacuum holder type lifting apparatus according to claim 1,characterized in that the first saw tooth control element of thechange-over valve comprises slits guided selectively to ribs formed on ahole of a cylindrical body arranged beneath the valve seat opposed tosaid valve body, and the pair of teeth include first and second teethformed adjacent to said slits and having inclined planes withsubstantially the same angle of inclination, and that the second sawtooth control element comprises slits guided to the ribs formed on saidhole, and teeth formed adjacent to said slits and having inclined planeswith the substantially same angle of inclination of that of the firstand second teeth, said teeth being opposed to said first and secondteeth.

3. A vacuum holder type lifting apparatus according to claim 1,characterized in that the depressing portion provided at the lowerportion of the second saw tooth control element is always depresseddownwardly from the change-over valve body by a compression spring.

4. A vacuum holder type lifting apparatus according to claim 1,characterized in that the change-over valve includes a cylindricalcasing having the valve seat provided at the central portion thereofwith an opening, said casing having the upper and lower inner peripheralfaces thereof provided with internal threads, first cylindrical bodyprovided at the outer periphery thereof with external threads engagingwith the upper internal with the lower internal threads of thecylindrical casing, said second cylindrical body being provided at thecentral portion thereof with vent holes, an opening and ribs adapted toguide the first and second saw tooth control elements for up-and-downmovement.

# i 1 Q i

1. A vacuum holder type lifting apparatus comprising a substantiallylongitudinally disposed cylinder provided at the lower end thereof witha flexible holding pad co-operating with the plane of a body to beconveyed, a piston air-tightly received in the cylinder and operated tomove up-and-down, and a piston rod connected at the lower end thereofwith said piston and provided at the upper end thereof with a hoistfitting, said upper end of said piston rod projecting from the upperportion of said cylinder so as to be guided, characterized in that thevacuum holder type lifting apparatus includes a bottom plate disposedslightly inwardly of the cylinder from a plane defined by the peripheraledge of the holding pad, said bottom plate being pRovided with a venthole, and a change-over valve provided in the piston for selectivelyconnecting upper and lower spaces formed in said cylinder andpartitioned by said piston with each other, and that the change-overvalve includes a valve seat, a valve body opposed to said valve seat andsupported rotatably, means for biasing said valve body toward a valveclosing direction, a first saw tooth control element secured to thelower end of said valve body and provided at the lower portion of saidfirst element with at least a pair of circumferentially disposed teethdifferent in height from each other, and a second saw tooth controlelement provided at the upper portion thereof with teeth opposed to saidfirst saw tooth control element and provided at the lower portionthereof with a depressing portion opposed to the bottom plate.
 2. Avacuum holder type lifting apparatus according to claim 1, characterizedin that the first saw tooth control element of the change-over valvecomprises slits guided selectively to ribs formed on a hole of acylindrical body arranged beneath the valve seat opposed to said valvebody, and the pair of teeth include first and second teeth formedadjacent to said slits and having inclined planes with substantially thesame angle of inclination, and that the second saw tooth control elementcomprises slits guided to the ribs formed on said hole, and teeth formedadjacent to said slits and having inclined planes with the substantiallysame angle of inclination of that of the first and second teeth, saidteeth being opposed to said first and second teeth.
 3. A vacuum holdertype lifting apparatus according to claim 1, characterized in that thedepressing portion provided at the lower portion of the second saw toothcontrol element is always depressed downwardly from the change-overvalve body by a compression spring.
 4. A vacuum holder type liftingapparatus according to claim 1, characterized in that the change-overvalve includes a cylindrical casing having the valve seat provided atthe central portion thereof with an opening, said casing having theupper and lower inner peripheral faces thereof provided with internalthreads, first cylindrical body provided at the outer periphery thereofwith external threads engaging with the upper internal threads of thecylindrical casing, said first cylindrical body being provided at theupper portion thereof with vent holes and a spring casing receivingtherein a compression spring adapted to always depress the valve body,and a second cylindrical body provided at the outer periphery thereofwith external threads engaging with the lower internal threads of thecylindrical casing, said second cylindrical body being provided at thecentral portion thereof with vent holes, an opening and ribs adapted toguide the first and second saw tooth control elements for up-and-downmovement.